A solar field typically includes a plurality of rows of solar panel arrays. A solar panel can generate 20-50 VDC at a current of 6-10 A. Each solar panel array can have several solar panels joined together to generate a desired voltage (e.g., 600 VDC or 1000 VDC). For example, an array with twelve solar panels wired in series, each generating 50 VDC at 8.5 A, can generate a voltage of 600 VDC at a current of 8.5 A.
FIG. 8 shows an exploded view of an example prior art row of solar panel arrays 10. Row 10 includes a plurality of solar panel arrays, including arrays 12 and 14. Each array 12, 14 includes a plurality of solar panels 16, for example two rows of six panels, or twelve panels. Each array is coupled directly to a combiner box 20, generally through fuses in the combiner box 20. The combiner box 20 combines the current from each of the arrays in series to produce a high current (e.g., 8.5 A×18 arrays=approximately 155 A) at the desired voltage (e.g., 600 VDC). The combiner box 20 can be a great distance from specific arrays. For example, if FIG. 8, arrays 12 and 14 are shown to be 378 feet and 357 feet away, respectively, from the combiner box 20.
The conductors used to carry current from the arrays to the combiner box vary in size from wires or cables carried in conduits to thick metal bars (bus bars). The cross-sectional area of the conductor (e.g., wire gauge) necessary to carry current from a specific array to the combiner box depends on the amount of current it is to carry and the distance from the array to the combiner box. In FIG. 8, the combined cross-sectional area of the example conductors is 137 mm2.
Wiring a solar field can require a large amount of resources and labor. The conductors carrying current directly from each array to the combiner box is lengthy and thick, requiring a large amount of metal. If row length is approximately 378 feet from the combiner box, each row includes 18 arrays, and the field includes 16 rows of arrays, the field may require on the order of 20 miles of wire. Because the conductors must carry current across a great distance, the total cross-sectional area can be large (e.g., 137 mm2 in the example of FIG. 8). Since wire gauges are sold in standardized sizes, if the precise cross-sectional area is not available, a larger-than-necessary gauge may be required, adding to the materials cost.
Installation of a solar field requires skilled electricians. For each pair of conductors, a conduit must be separately run from the array to the combiner box. Two wires (e.g., for positive and negative current) are run through each conduit from each array to the combiner box. This requires a large amount of labor and is difficult to trouble shoot and maintain. Moreover, each conductor is typically fused at the combiner box, potentially exposing the electricians and maintenance personnel to live electricity when the arrays are exposed to sunlight.